This invention relates generally to exhaust silencer systems and more particularly to a system having a muffler and a muffler bypass, the flow through which may be automatically varied by means of water filling the bypass at low and moderate engine speeds, the water being expelled and thus opening the bypass to the flow of exhaust gases at high engine speeds thus eliminating or reducing back pressure on the engine.
In a piston type internal combustion engine, exhaust gases are discharged from the engine cylinders, one after another, in a continuous series of loud explosions. The frequency and noise level of the explosions varies more or less in accordance with the engine speed and the load. Conventional mufflers, to be effective in eliminating or reducing the noise, necessarily but undesirably increase the back pressure on the engine resulting in impairment of the performance of the engine, particularly at high speeds where there is a high rate of gas flow through the muffler. These conventional mufflers cannot adjust themselves to the different operating conditions of the engine and effect a compromise between the desired degree of silencing and the objectionably high back pressure condition. It is therefore desirable to design an exhaust silencer system which gives a high degree of noise reduction and low back pressure at the moderate engine speeds generally used, but have means for automatically reducing the higher pressure occurring at high speeds.
Prior art systems generally have a muffler and a bypass or muffler cut-out valve which may be manually opened when exhaust back pressure exceeds a certain limit. These manually controlled bypass valves are subject to corrosion from the corrosion by-products in the exhaust gases and are subject to frequent failure. Furthermore, neglecting to manually operate the bypass valves results in degradation of engine performance.